In data communication systems, it is often useful to modularize interface electronics and other interface elements into a data communication module. For example, in an optical data communication system, an optical data transceiver module may include a light source such as a semiconductor laser, and a light detector such as a photodiode, and may also include driver and receiver circuitry associated with the laser and photodiode, as well as optical elements such lenses and reflective elements. The laser and associated circuitry convert electrical signals that the module receives via electrical contacts into optical signals that the module outputs via one or more optical fibers. The photodiode and associated circuitry convert optical signals received via the one or more optical fibers into electrical signals that the module outputs via the electrical contacts.
In one common type of optical transceiver module, an opto-electronic device (i.e., laser or photodiode) is mounted on a leadframe. Electrical contact pads on the opto-electronic device (die) are wire-bonded to contact pads on the leadframe. The leadframe, opto-electronic device, and wirebonds are then encapsulated in an optically transparent resin. This type of optical transceiver module is generally unsuitable for high-frequency operation (e.g., above 1 gigabit per second date rate) because the circuitry is susceptible to electromagnetic interference (EMI), which can adversely affect its operation.
Another common type of optical transceiver module, which is better suited for high data rates, includes a package commonly referred to as “TO” or “TO-can” due to its generally cylindrical shape. A TO-can package is characterized by a short cylindrical or can-shaped metal housing that provides EMI shielding. An outer metal EMI cage can be included around such a TO-can transceiver module to provide additional EMI shielding. An example of an optical transceiver module having such an outer metal EMI cage is a transceiver module of the family commonly known as Small Form Factor (SFF).
Optical transceiver modules of the SFF family may be too large or too uneconomical for some applications. It would be desirable to provide a small and economical optical transceiver module having EMI shielding.